Adults who are referred for bariatric surgery at any of these hospitals can take part in the study. Patients are given some information to read about the study and the chance to discuss it with the health professionals on the team. Those who agree to take part will have an equal chance of being assigned a gastric band, a gastric bypass, or a gastric sleeve. This allows the three types of operations to be compared in a balanced way. Participants will be told which operation they have been assigned to several weeks before their actual operation date. It is planned that 1341 patients will take part in the study in total.

After surgery, participants will be followed up carefully, including regular weight checks. They will be asked to complete questionnaires about their quality of life and use of healthcare. Some participants will also be interviewed about their experience. Researchers will also ask participants to provide two blood samples for future research into obesity, in addition to the samples people would give as part of their normal care. All participants will be followed up by the study team for three years.

The study is coordinated from the Clinical Trials and Evaluation Unit at the University of Bristol and involves a team of experts, including researchers from the Universities of Bristol, Birmingham, Oxford, and Southampton, and health professionals from each of the study hospitals. The study started in 2012 and will run for approximately eight years, until the final patient has completed follow-up. The study is funded by the National Institute for Health Research Health Technology Assessment Programme (ref: 09/127/53).

A map of By-Band-Sleeve recruiting centres

The By-Band-Sleeve study is aiming to compare the three different types of operations to find out which is most effective. The results of this study will be used to improve the information available to people considering bariatric surgery in the future, which will help with decision-making between health professionals and patients. The results will also be used to inform NHS commissioners about the most effective and cost-effective operation.

Chart of participant recruitment to By-Band-Sleeve

The above graph shows the number of participants that have joined the study so far (green stars) and the target number of participants that we would expect for this stage in the study (dashed line). The total number of participants that have agreed to take part as of 16th March 2018: 987